Hydraulic motor unit



50ct. 6,` 1936. l.. L. sHAUER 2,055,999

H'YDRAULIC Moron lUNIT Original Filed June 14, 1932 3 Sheets-Sheet 1 .in-ana;

ATTORNEYS m O/ /f N i) N n m C u J. OMR( m m w,

Oct. 6, 1936.

L. L scHAul-:R HYDRAULIC mon-UNIT origina Filed June 14, y1932 3 Sheets-Sheet 2 wi QN MM MH,

ATTORNEYS Oct. 6, 1936. 1 scHAuER AIWDRAULIC MOTOR UNIT AOriginal Filed June l, 1932 3 She'ets-Sheet 3 A Patented Oct. 6l 1936 UNITED STATES g 2,056,909 HYDRAULIC Moron UNIT Lawrence Lee Schauer, -Wyoming, Ohio, assignor to The Cincinnati Bickford Tool Company,

Cincinnati, Ohio, a corporation of Ohio Original application June .144, '1933, Serial No.

Divided and this application February 1o, 1934, serial No. 110,698

5 claims. (ci. 121-42) This invention relatesto improvements in hydraulic transmissions and is a division of my copendlng application, Serial No. 675,652, led June 14, 1933. Theinvention is concerned more par- 5 ticularly with the conversion of fluid energy into mechanical energy with a greater degree of emciency than has heretofore been obtained.

Other objects and advantages will be in part indicated in the vfollowing description and in part rendered apparent therefrom in connection with the annexed drawings.

In the attainment of the objectives of this invention, it is proposed to construct a'motor unit made up of a casing and a plurality of rotor elethe vdrill spindle. In such a case the motor unit, therefore, is preferably splined or keyed directly thereto in such manner as to permit movement of the spindle in an axial direction under the action of suitable feed mechanismwhile the spindie is being driven by the hydraulic motor. In other types of machines vthe vspindle or other driven element may not move axially relative to the unit and therefore the splined connection may be dispensed with.

Selector valve means are provided for effecting major speed changes and which when placed'in one position, directs the supply iluid to butone of the rotors thereby to drive sameand effect aV relatively high rotary speed to the driveneleme'nt, or if the valve'y is set in another position two' rotors are actuated by the same lvolume of oil and af' different rate o f movement ensues; or if the valve is in a; third position a third rotor is connected 'into the system and a third speed is obtained.V

mediate those produced by the selector valve and thus render the mechanism capable of variations ing machine, the element driven will usually be greater detail.

in speed from zero to maximum by increments innitesimal.

To enable others skilled in the art soifully to apprehend the 'underlying features hereof that they may embody the same in the various ways 5 contemplated by this' invention, drawings def picting a preferred construction of motor and a typical embodiment thereof in a machine tool have been annexed as a partof this disclosure and, in such drawings, like'characters of reference 10 denote corresponding parts throughout all the views, of whichzl Figure 1 isan illustration of arepresentative type of machine tool incorporating the present invention.y 1

l Fig. 2 is anenlarged detail, in verticalsection, of the motor unit.

Fig. 3-is-a plan viewof the unit with` the cover removed. y

Figs. 4 and 5 are horizontal sectional views of the unit taken along lines 4 4, 5-5 respectively Of mg. 2. A

Fig 6A is a plan rotor valve plates; and Fig. 7 is thereof along lines 7 1.' A

Fig. 8 is a sectional View of the selector valves and oil circulating valve whichgtogether control the iiow of oil through andwithin the motor unit.

Fig. 9 is a circuit diagram of an hydraulic system.

Fig. 10 is a perspective view ofone of the van'es i of a rotor.

'Referring now more particularly to Fig. 1 of the drawings, for convenience a representative type of machine tool, namely, a'drllling machine,v isl illustrated and to which this invention is peculiarly adapted. In general, the drilling machine comprises a base or support i and amupstanding column 2 upon'which a work support 3 and a tool head 4 are adjustably mounted. The upper end of the column 2 has mounted thereon view of one of the rotors. and

a 'sectional vier:

' the hydraulic driving motor unit M that rotates the spindle 5 and which will later be explained in 'I'he motive powerto effect f eed movements' of the spindleis taken from the spindle as by means of the bevel gears 6 and i* v.fand which through shaft 1, change speed mech- Janisin 8; shaft 9, bevel gears I0 rotatesl the power feed shaft I I in a forward or reverse direction depending upon the direction of rotation of the ,w i

spindle. S- y 'I'he lower end of the feedshaft is journaled in the adjustable head l4 and is operatively con-l nected with the spindle feed mechanism also carried by the head, The features nf this por-l tion of a suitable spindle feed means forms no part of the present invention and is set forth in greater clearness in United States Patent No. 1,746,265 to which reference may be had for fur' ther details. Briefly, it includes a swing or drop shaft f upon which is mounted a worm gear f1 and a bevel gear fz. I'he gear fa engages a, gear f: on the feed shaft and is driven thereby. When the drop shaft f is moved and latched into power feed position. the geAr f1 rotates worm wheel fr which .in turn rotates a pinion shaft fs. 'I'he inner end of the pinion shaft is provided with a pinion fa that meshes with rack teeth f1 formed upon the spindle sleeve and in this way the spindle may be elevated ory lowered by power. Tripping'mechanism, indicated generally, as t is provided for disconnecting the worm fr from the worm wheel f4 automatically when the spindle has been fed the proper distance. A hand wheel or lever fs secured to the shaft .f5 provides means for effecting feed or traverse movementsV of the spindle which is atall times counterweighted by the mechanism c.

The hydraulic driving motor M for the spindle is mounted on the colunm preferably at the upper end thereof -and-in axial alignment with the tool spindle 5, and comprises a 3-part casing I5, I5b and I5. The upperl and lower sections I5l and I5 provide the bearings for supportingl the upper end of the shaft 5 and other mechanisms later to be referrerd to, and the center section I5b provide the motor housing proper within which a plurality of rotors A, B and C are contained.

Each of the rotors, A, B and C 4is splined orl otherwise secured to Va non-translatable sleeve member 23 which, in turn, has a keyed or splined connection with the spindle shaft 5, the ends of the sleeve 23 being rotatably mounted in iournal bearings 24 and 24 provided by the upper and lower sections I5* and I5 of the motor unit. In thisway rotary movement of the rotor or rotors is transmitted directly to the spindle shaft, the latter being mounted as to be freely movable endwise in the sleeve 23 under the action of the manual or power feed mechanisms hereinbefore mentioned to effect the feed action. Referring to Figs. 2,' 4, 5 and 6, it will be noted. that the motor housing I5b is formed with a ceny trai aperture I5 within which are keyed or other-v wise lsecured a plurality of slotted ring members I'I, I'Ib and I1. Each of these'nings is isolated from the one adjacent by grooved discs I8 and in eect provides a single cylinder for the vanes of its respective rotor. Each ring is also provided with intake and discharge ports or `slots I9si and lsb; oppositely ldisposed and in registry with intake and discharge channels 20* and 20h respectively that are formed in the housing |51.

Figs. 4 and 5 illustrate more 'clearly the con-'- 65 tstantial thickness and which is provided with a plurality of radially disppsed slots zu.` nach slot ais provided'with a reciprocably mounted blade member 2I'. of the same.' width as the rotor element.

is enlarged beyond theperiphery of the disc B thereby forming .a chamber or cavity 22 betweei the rotor .and the ringiwithin which the vanes or'pistcnsfil, made preferably of wear resisting t material,4 are adapted to be cyclically extended.

`. lA section ofthe inneisurfacef of the ring Il v by means later to b'e described. AThe near ends of the slots I9* and I9b are spaced apart a distance slightly greater than the distance between at least two of the blades 2i in the rotor so that l there will always be one blade projecting into the cavity 22 preventing direct communication between the inlet anddischarge ports I9* and I 8b as the rotor turns.

Each end wall of the arcuate cavity 22 is inclined as at 22 and`22" to permit the blades 2l to move without shock into and out of their eifec- Vtive working positions.

To drive the rotor uid under pressure-is directed intozconduit 20" and from there it flows through slot I9* into expansion chamber 22 behind one of the blades! I. The continued application of the fluid pressure acting against that portion of the vane 2| exposed, moves the vane forward in the chamber 22 until the next-following vane closes on or passes the end of the intake slot I9'. 'I'he succeeding vane then becomes subjected tothe action of the incoming pressure fluid and co tinues to turn the rotor. When the preceding blade has beeny moved a distance sufficient to uncover port I9b`the fluid trapped between the successive vanes-is permitted vto discharge therein and as the rotor advances further the vane is cammed inwardly by the inclined walls 22" and retained in its retracted position by the inner wall of the ring I1. After the succeeding vanes have been moved in this manner the first vane reaches' the inclined wall 2i where it once more moves 'outwardly to its effective working position and the cycle is again repeated.

During a complete revolution of a rotor supplied with a plurality of vanes as shown, each vane, it will be noted, not only acts as a piston moving in the wort: chamber 22 but each vane also partakes of the functions of a valve so that proper and timely valve action is automatically obtained between the common intake and discharge ports.

The amount or quantity of fluid transferred from theintake port to the discharge port for each revolution of therotor, will, with a fourteen yane rotor, be fourteen times the volumetric capacity of the chamber 22 between two vanes, for a five vane rotor, five times the capacity of the chamber, for a nine vane rotor, nine times the capacity and so on; and if thel rate of flow of fluid directed'to the intake conduit 2li is volumetrically constant it follows that the rate of movement of the rotor will be whereR" represents the rate in revolutions per minute, Q represents the quantity supplied in cubic inches per minute, V the volume ofl one of the chambers between two blades, and. N the number of vanes or blades.

Variations in rate of rotation may beeiected in various ways, such as, for example', reducing the rate-of delivery of the pump or by-passing a portion of the flow througha pressure relief valve, but as these methods reducethe efficiency of the motor unit and result in large power losses because of friction and heating of the oil, such arrangements are not entirely satisfactory especiallyso in installations requiring a wide range of speeds. AIt is the object of this invention to provide 'a structure that may be driven'at various preselected speeds without the'ill effects mentioned above.

To this end I have arranged a plurality of rotors on the shaft to be driven and provide valve means forl selectively directing the supply fluid to as many as desired. By arranging the valve in such manner as to connect at will two or more rotors in parallel, the amount or quantity of fluid supplied to any one rotor is materially lessened and a reduction in rate of movement of the driven shaft results. If two rotors of equal displacement or capacity are connected in parallel the new rate will be half that of one rotor; if three rotors are in parallel the new rate will be reduced to one third the rate of one rotor or two thirds the rate of two rotors; four rotors will produce a rate one fourth the rate of one rotor and three fourths the rate of three rotors, and so on.

'I'he more rotors connected to the supply line the greater is the reduction in speed of the driven y shaft and, it will be observed, each reduction in speed of the driven shaft is accompanied by a proportionate increase in torque or turning power of the shaft. In machine tool applications this is particularly advantageous in that the larger tools which normally should be driven atreduced or slow speeds should also have increased power instead of reduced power and inasmuch as there is no by-passing of fractions of the propelling medium under the increased pressures there is no loss of power resulting from that source.

The above applies only to the major changes in spindle speeds and is based upon the assumption that all of the rotors are of equal size and volumetric capacity. However, in such cases wherein it is desired to obtain various spindle speeds other than in simple harmonic progression, accompanied by disproportionate changes in shaft torque, it is proposed to connect various rotors of which the working areas of the respective vanes differ in size.

Referring to Fig. 2, let it be assumed that the working surface of the vane 2l in the work chamber 22 of rotor A represents a given area, it will then be noted that the effective area of the vane in the worlr chamber of rotor B is somewhat larger. Consequently, the fluid pressure acting upon the larger piston-like area will set upa greater turning moment upon the driven shaft than will the same pressure acting upon the smaller vane area of rotor A. And when both rotors A and B are connected in parallel the total torque on the shaft 23 is the combined force of the small rotor A and the large rotor B, and thus there may be effected major changes in speed which are disproportionate to each other and to the ultimate power value in the output shaft.

For larger and heavier classes of work a still further increase in turning power is desirable and to accomplish that end the diameters of the rotors may be varied as will now be explained.

Referring to Figs. 2, 4 and 5 it will be observed that the vanes of the rotor B, in addition to the fact that they are of larger effective area. than the vanes of rotor A, are radially disposed furtherl from the axis of rotation. As a consequence, the unit force acting upon the vanes ofv rotor B produces a greater turning force upon the shaft 23 than does the same unit force acting upon the varies of rotor A.

As before explained, and in drilling machine tools particularly, the larger tools should be driven at slow speeds but with increased power, and by arranging a multiplicity of rotors of various sizes and capacities in the manner set forth above, the spindle may be rotated at various predetermined speeds, each one of which will be accompanied by change in power value commensurate with the increased or decreased speed.

In the drawings but three rotors, A B and C are vdepicted which will serve to illustrate the principles of this invention but it will be understood that any number of rotors may be employed to give the desired range of speeds to the driven shaft.

The coupling ofthe various rotors maybe effected in any suitable manner. I have preferred, however, toconstruct the unit with av selectorvalve built into the main casing so' that any leakage that may occur about the rotors or -valve takes place inside the main casing where it may serve as a lubricant and thereafter be drawn off as explained later. y v

Referring to Figs. 2, 4 and 8 the inlet and outlet ports of the motor unit are designated as 25 and 26 respectively, each of which communicate directly with an improved form of selector valve means. This valve means comprisesl three plungers V1, V2, Va arranged in parallelism and slidable in bores V1, V2 and V3 formed in the sections i5EL and I5b of the casing. Intermediate the ends of inlet and exit plungers. V1 and V3 reduced portions 21 and28 4are formed .which provide chambers for the passage of ,iiuidvtherearound. The surface of by-pass plunger V2 is unrelieved for a purpose later to be explained.

The inlet and outlet conduits 20@ and 20h, of each rotor communicate with the valve cylinders V1 and V3 respectively and when all valve plungers are in the position shown in Fig. 8, fluid from vthe supply conduit enters port 25, around reof the three valve plungers are arranged to uncover cross-ports 21a and 28a so that there is a free passage between the inlet andV outlet chambers of these rotors.

A control lever L provides convenient means f or controlling the positioning of the triple plunger valve mechanism. As shown in Figs. 2 and 8 the upper end of the lever is secured to a shaft 32 journaled in the section I5 of the unit. Short levers 33a and 33b also connected to the shaft 32 have their free ends slidingly connected as at 34 with the valve rods V1, V2 and V1 land thus when the control lever is` oscillated the three valve plungers are reciprocated simultaneously. Spring detent means 35 associated with notches 36 on valve plunger V: serve as the retaining means for the valves.

The valves are illustrated in these figures in their extreme upward position whereupon only the rotor A is connected in the system. If the control lever L be actuated and the three valve plungers V1, V2 and V3 lowered one position the intake and discharge channels 20! and 20" of the rotor B are also connected into the system in parallel with the rotor A. In this position the bypass valve plunger V2 closes or stops the flow in the crossport 2'!8L and isolates the intake and discharge channels of the rotor B.

Both of the rotors A and B now-receive fluid from the common intake port 25 and since the volume of fluid supplied to the inlet port now drives two rotors instead of one, the rate of movement of the driven shaftv is reduced.

When the valve plungers are moved downwardly to a third position, cross port 28HL is closed and the intake and discharge ports of rotor C are connected into the system, and a further major reduction-in spindle speed results. Each -reduction inspindle speed, it will be seen, is accompanied by an increase in the power output, firstly because of the increase in the area of the vanes of rotors B and C over the areas of the vanes of rotor A and secondly because vof the increased lever arm of rotors B and C over the lever arm of rotor A. To facilitate movement of the plungers V1, V2, Va and to provide a drain for leakage, the lower ends. of the chambers V1, V2 `and. V3 communicate with each other and with line 29 leading to the reservoir R. Any surplus oil accumulating in the upper or lower sections of the unit passesthrough conduits 30 and 3| to drain pipe 32.

From a practical standpoint a large number of rotors have certain disadvantages, for example, space limitations, weight, cost of manufacture, et'c., and to obviate such difficulties it is proposed to employ a fewer number of rotors and insert in one of the fluid conduits a device for throttling or regulating the rate of flow of the'fluid therein.- By adjusting the throttle various rates, intermediate those accomplished by the selective coupling of the rotors, may be effected with but little loss in power.

Fig. 9 illustrates diagrammatically one such type of hydraulic circuit for accomplishing that end. In this figure P represents a pump or other normally constant source of fluid, usually oil, and R a reservoir from which the pump derives its fluid through the line 40. The discharge side of the pump is connected by line 4| with a reversing valve RV which reverses the direction of flow in lines 42 and 43 connected with the ports 25 and 26 respectively of the motor unit.

With the reversing valve in the position indicated in Fig. 9 the propelling iiuid passes through line 42 to the intake port 25 of the rotor unit M. The fluid leaving the motor passes back to the reverse valve through the line 43 and thence to the reservoir R byway of line 44.

When the reverseY valve is moved to the other position (dotted line position in Fig. 9) line 43 is connected to line 4| and becomes the forward pressure line and the line 42 is connected with line 44'and becomes the return line.

For the purpose of effecting various rates of speed intermediate those produced by'the selective coupling of the rotors, a throttling device T is embodied in the circuit, the function of which is to effect variations in the rate of flow of the liquid through the motor M. As illustrated in the drawings, the throttling device T is preferably placed in an oil diverting conduit 45 connected with the forward-'pressure line 4| and in the present case comprises a valve mechanism having a regulatable flow orifice. When the throttle T is closed, the entire discharge of 4the pump P is caused to pass to the motor M, as hereinbefore explained. However, when the throttle T is wholly or partly opened a fraction of the pump discharge passes through the branch line 45 to the reservoir thereby diminishing the flow in the main branch 4 le leading to the motor. In this way the'volume of fluid supplied to the motor may be varied thereby to cause variations in its rate of movement.

Under normal conditions of operation the throtproportionately tle T is set so as to oder a resistance to the flow in the branch line 45 substantially equal to the resistance encountered by the motor M when under load so that the ratio of the flows in the two branches will remain constant and hence the rate of motormovement constant.

By adjusting the resistance of throttle T the ow from the source P may be suitably apportioned between the two branches and since one of the barnches conducts propelling uid to the motor, the motor may be operated at various intermediate rates of speed.

As the percentage of the oil to be by-passed will besmall, as compared with the amount utilized in driving the rotors the finer or intermediate speed changes are effected with but little loss in hydraulic power. It will be noted also that as more rotors arev connected into the system, the percentage of the oil by-passed by reason `of anv adjustment of the throttle T, decreases.

Consequently, when driving large tools at intermediate and low speeds, the power losses occasioned' by by-passing a. small percentage of the totalv'lume supplied to the motor is comparatively slight. To guard against excessive pressures occurring in the system the relief valve r is provided.

Any suitable means, such as springs, cams, etc. may, of course, be employed cyclically to project the vanes 2| of the rotors to their normal working position. I have preferred, however, to use hydraulic fluid pressure acting at the rear of the various vanes for accomplishing that purpose.

Referring more particularly to Figs. 2, 4, 6 and 7, the fluid entering the conduit 2|) and slot I 9* to drive the respective rotors forward also enters branch ports 46 which lead to arcuate passages 48 by way of radial passages 41. 'I'he arcuate passages 48 are disposed at the rear of the vanes and communicate with the chambers 2li behind the vanes. Each vane is preferably provided with a tang 2|, as shown most clearly in Fig. 10, to insure that the recess 20 will always communicate with the passages 48 when the vane is in proper angular position. As represented in dotted lines in Figs. 4, and 6, the arcuate ports 48 extend only part way around the surface of discs I8, beginning at a point slightly in advance of inclined wall 22' and ending a short distance beyond the end of theinclined wall. By this means fluid pressure supplied by the pump acts upon the inner ends of the vanes and forces them outwardly thereby to assist in the rotation of the rotor and to maintain each vane in its outer working position until its succeeding vane becomes effective. After this point is reached the chamber 20 of the rst mentioned vane is cut off from the supply channel 48 and communicates with/ another set of annular channels 49 connected with the discharge conduit 20|. Thus, as the rotor advances and the blades are caused to recede, the fluid at the rear thereof is ejected into channels 49, thence through conduits 50 and 5| to the discharge conduit 20". When the direction of rotation is to be reversed the conduit 20b becomes the highjpressure conduit and the flow to the rear of the vanes is also reversed, as will be understood.

While the drawings illustrate the vanes of the respective rotors in the same angular position it will be understood that by staggering the rotors with respect to each other a continuous and more steady drive free of pulsationsvand vibratcry efto said bore and normally fixed against vmove 1 chamber ineach cylinder liner being of a difassemmy also being provided with a liquid intakeA l port tangent to one end of the power chamber `formed thereinand a liquid exhaust port tan'y it for various utilizations by retaining one or more 'of the features that, from the standpoint of the prior art, fairly constitute essential characteristics of either the generic or specific aspects of this invention and, therefore, suchv adaptations should be, and are intendedto be,'comprehended within vthe meaning and range of equivalency of the following claims.

' Having thus revealed this invention, I claim as new and, desire to secure the following combinations and elements, or equivalents thereof, by Letters Patent of United States.-

1. A variable speed hydraulic transmission combining a casing member having a central bore formed therein; ay driven shaft journaled in said pasing concentric with the axis of said bore; a plurality of independent motor units of equal external diameter fitted'within said bore, each lying'in the plane of the stator and rotor elements, and a pair of cover plates sealing -,each of said units against leakage of propelling liquid from one unit to another; said units constituting complete assemblies of different capacities) and adapted to be inserted in said casing in any order selected, said casing memberalso having formed therein a plurality of pairs of conduits in parallel spaced planes, each pair of conduits comprising a supply conduit intersecting and tangent to the intake port of an associated motor unit., and a discharge conduit intersecting and tangent to Athe 'exhaust port of an associated motor unit, a

main supply 'conduit in said casing common to all of said motor unit supply conduits, and a main discharge conduit in said casing common to all of said motor. unit discharge conduits; and valve means in one of said main conduits for controlling the iiow of propelling liquid through said motor f 2. -A variable speed hydraulic transmission combining a .casing member having a central bore formed therein; a sleeve member journaled in said casing concentric with the axis of said bore; a shaft member translatable in said sleeve; a plurality of individual motor units of equal `outside diameter mounted on said sleeve, each of said units comprising a cylinder liner fitted ment relative `to the casingand having a power chamber of a ghlen size formed in its inner periphery at one side of a medial plane, the power ferent radial extent, a rotorelement in each assembly splined to said sleeve and provided with a` plurality of reciprocable `vane members adapted to cooperate with said power chamber, each gent to the 'other -end f said power chamber, and a. pair of 'cover plates sealingeach of Sarg assemblies against leakage of propelling liqui from one Aassembly td'another; said casing mem-I ber also `having formed therein a pluralityl of sets of liquid conduits, one set for each assembly, and each set of conduits comprising a supply'conduit intersecting and tangential to the intakel port of an associated assembly, and a'discharge conduit intersecting and tangential to theex haust port of the associated assembly; a main supply conduit common to all of said supply conduits; a main discharge conduit common to all of said discharge conduits; and valve means in one of said main conduits for selectively controlling the ow `of pressure liquid from said liquid supply combining a casing member; a

driven shaft journaled in said casing; a plurality of individual motor units of different hydraulic capacities mounted on said shaft, each of said v units comprsing -a non-rotatable stator element of the sarnei1 outer diameter and each having a power-chamber of a different radial extent formed therein at one side of` a medial plane, a rotor element operatively connected with said shaft and provided with a plurality of reciprocable vane members adapted to cooperate with the associated power chamber, a liquid intake port tangent to one end of said power chamber and a liquid exhaust iport tangent to the other end of said power chamber, both of said ports lying in the'l plane of the /stator element, said casing member also having formed therein a pair of parallel con- A duits individual to each of said units, each pair of conduits comprising a supply conduit intersecting and tangent to the intake port of one of said units, and a dischargeconduit intersectin'g and tangent to the exhaust port of each of said units; a main supplyconduit common to all of said supply conduits and` a main discharge conduit common to all of said discharge conduits; and valve means in said conduits vfor controlling the flow of propelling liquid through selectedtpairs of said conduits to eifect propulsion of the motor unit associated therewith; and means for isolating the motor units not connected in the circuit from said main supply and discharge conduit.. 1

4. A variable speed hydraulic transmission combining a casing member having a central bore formed therein; a sleeve member journaled in said casing concentric with the axis of said bore; Ya shaft member translatable in said sleeve; a plurality of individual motor assemblies mounted in said sleeve, each of' said units being of the same external diameter to i'lt said bore,` and each comprising a statorA element normally fixed against movement relative to thecasing vhaving a power-chamber formed in vits innerperiphery at one side of a medial plane, each of said power chambers being of a different radial extent, a rotor element splined to said sleeve and provided With a plurality of reciprocable vane members adapted to. cooperate with said power chamber, each assembly also being provided with a liquid intake and a liquid exhaust port in communication'with its respective power chamcomprising a supply conduit intersecting the intakeport of an associated assembly. and a discharge conduit intersecting and the exhaust port of the associated assembly; a main supply'conduit common to all of said Supply conduits; a main discharge conduit common to all oi' said discharge conduits; a constant delivery source of propelling liquid; valve means in one o! said main conduits for selectively controlling the ilow of pressure liquid froml said constant source through one of said motor' assemblies exclusively to effect a given rate of rotation ofthe shaft or through two or more of said assemblies in'iultaneously to effect a different rate of' ro ation of the shaft; and means for diverting a fraction of the ilow of liquid from said constant source to effect intermediate variations in the speed of the transmission. l.

5. A` variable speed hydraulic transmission adapted tobe driven from a constant source oi" liquid supply combiningl a casing member: a

aosacco o 'Iormed therein oi'ia diilerent radial Jextent, a

rotor element operatively j connected with said shaft and provided'with a plurality of reciprocable vane members adapted .to cooperate with its associated power chamber, a liquid intake port communicating with one end ci said power chamber-and .a liquid exhaust port communicating with the other-end of .said power chambensaid casing member also having formed therein aI 'pair'oi .conduits individual to each oi' said units.

each pair oi conduits comprising a supply conduit intersecting theintake .port of' one oi' said units. and a discharge conduit intersecting the exhaust port-of -eachof said units: a main supply conduit common to: all of said' supply conduits, anda I5 v main..discharge`conduit common to all o! said discharge conduits; and valve means in said conduits for controlling the now o! propelling liquid through selected pairs of said conduits to the motor unit associated 2 0 effectpropulsion of therewith. Y i

4LAWRENCE LEE SCHAUER.

lil- 

